This application claims priority of Korea patent Application No. 99-57402, filed on Dec. 14, 1999.
(a) Field of the Invention
The present invention relates to an operational control system for vehicles, and more particularly, to a vehicle speed control system using wireless communications and a method for controlling the same.
(b) Description of the Related Art
There are two main types of prior vehicle speed control systems. One uses a GPS (Global Positioning System), while the other uses RF (radio frequency) communications. In the vehicle speed control system using a GPS, after the position of a vehicle is determined, speed limit information corresponding to vehicle position is used to possibly alert the driver or control the vehicle. With the system using RF communications, the vehicle is controlled in areas where RF signals are received. Both these systems are still undergoing testing in Europe, Japan and other countries.
A drawback of the system utilizing the GPS is that road information of a uniform setting is used. That is, changes in road conditions are not taken into account. With the system in which RF communications are used, on the other hand, vehicle control is realized according to pre-installed road information, and each RF transmitter is controlled such that vehicle control is performed to match changing weather and road conditions.
However, a serious drawback of the system utilizing RF communications is that the system is limited to use in only areas where RF signals are received. Accordingly, a strong output is required by the RF transmitters, and, as a result, the same information may be transmitted to more than just the targeted vehicle. That is, unwanted control of a vehicle travelling in the opposite lane may result. Vehicle speed control is particularly problematic in areas where there are curves in the road.
The present invention has been made in an effort to solve the above problems.
It is an object of the present invention to provide a vehicle speed control system using wireless communications and a method for controlling the same in which vehicle control is possible with only a small output by a RF transmitter, and in which unanticipated vehicle control is prevented.
To achieve the above object, the present invention provides a vehicle speed control system using wireless communications and a method for controlling the same. The system comprises a driving state detecting unit for detecting steering angle, vehicle speed, throttle valve opening, brake operation, and turn signal operation, and outputting corresponding signals; a transmitter/receiver for outputting low-strength signals containing information of a speed limit and a range of the speed limit; an electronic control unit for receiving the signals of the transmitter/receiver and establishing an ISA mode if necessary, determining if a present driving state corresponds to a first driving state using the signals of the driving state detecting unit, determining if the driver has performed deceleration operations, and performing control into the first driving state if needed; an engine control unit for outputting signals for control of the throttle valve opening according to control signals of the electronic control unit; a throttle valve electronic control unit for receiving the signals output from the engine control unit and outputting electrical signals to a throttle valve to control an opening degree of the throttle valve; and a display for displaying a present mode and a vehicle state according to the control signals of the electronic control unit.
According to a feature of the present invention, the transmitter/receiver is provided adjacent to a specific lane, and the low-strength signals of the transmitter/receiver are such that vehicles traveling on the opposite lane do not receive the signals.
According to another feature of the present invention, the electronic control unit determines if the present driving state corresponds to the first driving state after establishing the ISA mode, enables full control of the vehicle by the driver if the present driving state corresponds to the first driving state, and control the display to output a warning message if the present driving state does not correspond to the first driving state.
According to yet another feature of the present invention, the electronic control unit determines if the driver has performed a deceleration operation during a predetermined interval after output of the warning message, enables full control of the vehicle by the driver if the driver has performed a deceleration operation, and performing control into the first driving state if the driver has not performed a deceleration operation.
The method for controlling the vehicle control system using wireless communications comprising the steps of receiving signals from an RF transmitter/receiver to determine if a vehicle is in a first driving state in a speed limit zone; establishing an ISA mode for control into the first driving state and performing display to alert the driver of such control; determining a present driving state, comparing the present driving state with the first driving state, determining if the present driving state corresponds to the first driving state, and performing display to inform the driver of the result of the comparison; determining if the driver has performed a deceleration operation if the present driving state does not correspond to the first driving state; disengaging the ISA mode and enabling full control of the vehicle by the driver if the present driving state corresponds to the first driving state or if the driver has performed a deceleration operation; and controlling an engine control unit via CAN communications if the driver has not performed a deceleration operation, engine control being performed such that a throttle valve is controlled to reduce the speed of the vehicle.
According to a feature of the present invention, the step of determining if the driver has performed a deceleration operation comprises the steps of (a) determining if the driver has depressed a brake, determining if the driver has released an accelerator pedal, or if the a throttle valve opening is less than a predetermined throttle valve opening; (b) determining if the driver has operated a turn signal if one of the conditions of step (a) is not satisfied; (c) determining if a steering angle is greater than or equal to 30xc2x0 if the driver has not operated a turn signal; (d) maintaining the ISA mode if the steering angle is less than 30xc2x0; (e) disengaging the ISA if any of the conditions of steps (a), (b) and (c) are satisfied.